Observations of intergranular corrosion in AA2024-T351: The influence of grain stored energy

Aluminium alloy 2024-T351 was examined using a range of electron microscope techniques at the early stages of attack after immersion in 0.1 M NaCl aqueous solution. At attack sites, a significant portion of the intergranular network was attacked, even though only 15% of the boundaries were decorated by second phase particles (θ-phase). Structure of the grains and the grain boundaries, including grain misorientation angle and grain stored energy, based on dislocation density, were probed further. A strong correlation of intergranular attack around grains with higher grain stored energy and therefore high dislocation density was revealed.

► Intergranular attack in AA2024-T3 exposed to 0.1 M NaCl was studied using EBSD.
► EBSD was used to determine the relative grain stored energy which is related to the defect density.
► Intergranular attack was most severe for grains with high grain stored energy.